Means for controlling the supply of liquid fuel to the combustion chamber of a prime mover



y 10, 1956 o. N. LAWRENCE 2,753,803

MEANS FOR CONTROLLING THE SUPPLY OF LIQUID FUEL TO THE COMBUSTION CHAMBER OF A PRIME MOVER Filed May 8, 1951 Fig.2

Fig.3

0.]YfLawnemC6 United States Patent MEANS FOR CONTROLLING THE SUPPLY OF LIQUHD FUEL TO THE COMBUSTION CHAMBER OF A PRHVIE MOVER Owen Napier Lawrence, Dorridge, England, assignor to Joseph Lucas Limited, Birmingham, England Application May 8, 1951, Serial No. 225,236 Claims priority, application Great Britain May 16, 1950 4 Claims. (Cl. 103-38) In some forms of jet engines or gas turbines provision is made for injecting water into the combustion chamber. This necessitates a concurrent change in the adjustment of the means for controlling the supply of liquid fuel, and the object of the present invention is to enable this requirement to be met in a convenient and satisfactory manner.

The invention comprises a governing means adapted to control the supply of liquid fuel to the combustion chamber, and responsive also to the control of a valve which is actuated when water is injected, for increasing the rate of supply of liquid fuel.

In the accompanying drawings:

Figures 1, 2 and 3 are diagrams illustrating three typical embodiments of the invention.

Referring to Figure 1, the governing means there shown is arranged in direct association with a liquid fuel supply pump of known construction. The pump is of the swash plate type, and comprises a rotor a contained in a hollow body part b. In the rotor are mounted a plurality of reciprocatory plungers c which at their outer ends co-operate with an angularly adjustable stationary swash plate d. The pump inlet a communicates with a fuel supply passage indicated by e and the pump outlet a communicates with a discharge passage 1 leading to the burners x.

In the embodiment of the invention shown by Figure 1, there is provided on the body part b of the pump a chamber which is divided into two compartments g, h by a flexible diaphragm i loaded by a tension spring j. Instead of a diaphragm, an equivalent piston slidable in a cylinder may be used. The compartment h is connected to the fuel supply passage e by another passage h In the compartment 11 is arranged a valve lever k loaded by a spring in and carrying a closure member n which controls a vent 0 leading to a liquid-operated servo-mechanism, the latter serving to control the rate of supply of fuel to the burner of the combustion chamber.

In the example shown the servo-mechanism comprises a cylinder p containing a piston q loaded by a spring r, the piston being connected by a rod s to the swash plate d of the pump. One end of the cylinder is in direct communication with the discharge passage 1 of the pump and the other end communicates with the said passage through a restricted orifice t, the latter end of the cylinder being also in communication with the vent 0. The arrangement is such that when the closure member 11 closes the vent, the piston q moves under the action of the spring r to the left for increasing the angularity of the swash plate and so increasing the pump output. When the closure member opens the vent, the preponderating liquid pressure acting on the left hand side of the piston moves the latter in opposition to the spring for reducing the pump output. Liquid passing out of the vent is returned to the inlet passage of the pump.

The other compartment g above mentioned receives liquid (which may be liquid fuel) from the interior of 2,753,803 Patented July 10, 1956 "ice the body part b to which liquid is supplied from the" pump inlet through radial passages as u in the rotor at a pressure which varies with and in proportion to the speed of rotation of the rotor. The liquid supplied from the body part b to the chamber g is conveyed through a passage g having therein a restricted orifice v. Also there is provided in another passage 10 interconnecting the said compartment g and the discharge passage f a throttle valve 2 which is operated manually or otherwise when water is injected to the combustion chamber, a re-- stricted orifice 3 being arranged in the passage 10 between the throttle valve 2 and the passage 1.

When no water is being supplied to the combustion chamber, the valve 2 is fully open. The diaphragm i is then subject to a pressure which is determined by the opposed pressures in the passage f and the pump body part b. Relative variation of these pressures will have the efifect of closing or opening the vent valve n, so causing the servo-mechanism to adjust correspondingly the pump swash plate. But when water is admitted to the combustion chamber, an increased fuel supply is required and this is effected by closing the valve 2. This, at a given speed of the pump, has the effect of reducing the pressure supplied by the pump through the passage restriction v and acting on the upper side of the diaphragm i, so causing the vent valve is to close and the servo-mechanism to move the swash plate in the direction for increasing the pump output.

The example shown in Figure 2, differs from the foregoing, in that the chamber 11 is connected to the pump discharge passage by the passage 10 and the throttle valve 2 is normally closed. Also the restriction v in the passage g leading from the pump body part b to the chamber g is omitted. Further a restricted orifice 4 is provided in the passage h leading from the chamber h to the pump inlet passage e. So long as the throttle valve 2 is closed, the servo-mechanism associated with the pump is subject only to the action on the spring loaded diaphragm i of liquid whose pressure is related to the speed of the pump. When water is admitted to the combustion chamber, the valve 2 is opened. Liquid is thereupon admitted to the chamber h from the discharge passage 1 causing the vent closure member n to close and the servo-mechanism to increase the pump output.

The arrangement shown in Figure 3, differs from that shown in Figure l, in that the throttle valve 2 is arranged in a passage 10 leading to the chamber g from the inlet passage e of the pump, and the restricted orifice 3 is placed between the throttle valve and the said chamber. Also the throttle valve is normally closed. During normal working conditions, the diaphragm z' is subject only to the pressure of the liquid supplied from the pump body part b. When water is admitted to the combustion chamber, the valve 2 is opened, causing a fall of the liquid pressure in the chamber g and the vent closure member 11 to close. The servo-mechanism then causes the pump output to be increased.

The invention is not, however, restricted to the examples above described. Also the servo-mechanism may be arranged to control the rate of supply of fuel to the combustion chamber otherwise than by acting on the pump. Thus it may be arranged to actuate a throttle valve or by-pass in the discharge pipe between the pump and combustion chamber.

Having thus described my invention what as new and desire to secure by Letters Patent is:

1. In a system for supplying liquid fuel to a prime mover, the combination of a fuel pump having a fuel inlet and a fuel outlet, fuel supply and delivery passages communicating respectively wtih said inlet and outlet, a liquid-operated servo-mechanism for controlling the I claim rate of fuel supply from said pump to the fuel delivery passage, a liquid-operated control device for said servomechanism, said control device including a chamber, a liquid-pressure responsive member dividing said chamber into two compartments, and means operable by said member for controlling said servo-mechanism, means including a third passage for supplying one of said compartments with operating liquid at a pressure which varies with and in proportion to the speed of said pump,

and thereby exposing one side of said member to the pressure of the operating liquid, a fourth passage connecting the other of said compartments to the fuel supply passage, and thereby exposing the opposite side of said member to the pressure in said fuel supply passage, one of the third and fourth passages having a restriction therein, a fifth passage also having a restriction therein and communicating at opposite ends respectively with one, of said compartments and one of said fuel supply and delivery passages, and a valve arranged in said fifth passage and operable for establishing and interrupting liquid flow through said fifth passage, and thereby varying the liquid pressure acting on one side of said member.

2. In a system for supplying liquid fuel to a prime mover, the combination of a fuel pump having a fuel inlet and a fuel outlet, fuel supply and delivery passages communicating respectively with said inlet and outlet, a liquid-operated servo-mechanism for controlling the rate of fuel supply from said pump to the fuel delivery passage, a liquid-operated control device for said servomechanism, said control device including a chamber, a

liquid-pressure responsive member dividing said chamber into first and second compartments, and means operable by said member for controlling said servo-mechanism, means including a third passage for supplying the first compartment with operating liquid at a pressure which varies with and in proportion to the speed of said pump, and thereby exposing one side of said member to the pressure of the operating liquid, said third passage having a restriction therein, a fourth passage connecting the second compartment to the fuel supply passage, and thereby exposing the opposite side of said member to the pressure in said fuel supply passage, a fifth passage communicating at opposite ends respectively with said fuel delivery passage and said first compartment, and a valve arranged in said fifth passage and operable for establishing and interrupting liquid flow through said fifth passage, and thereby varying the liquid pressure acting on one side of said member, said fifth passage having a restriction therein between said valve and said fuel delivery passage.

3. In a system for supplying liquid fuel to a prime mover, the combination of a fuel pump having a fuel inlet and a fuel outlet, fuel supply and delivery passages communicating respectively with said inlet and outlet, at liquid-operated servo-mechanism for controlling the rate of fuel supply from said pump to the fuel delivery passage, a liquid-operated control device for said servomechanism, said control device including a chamber, a

liquid-pressure responsive member dividing said chamber into first and second compartments, and means operable by said member for controlling said servo-mechanism, means including a third passage for supplying the first compartment with operating liquid at a pressure which varies with and in proportion to the speed of said pump, and thereby exposing one side of said member to the pressure of the operating liquid, a fourth passage connecting the second compartment to the fuel supply passage, and thereby exposing the opposite side of said member to the pressure in said fuel supply passage, said fourth passage having a restriction therein, a fifth passage communicating at opposite ends respectively with said fuel delivery passage and said second compartment, and a valve arranged in said fifth passage and operable for establishing and interrupting liquid flow through said fifth passage, and thereby varying the liquid pressure acting on one side of said member, said fifth passage having, a restriction therein between said valve and said fuel delivery passage.

4. In a system for supplying liquid fuel to a prime mover, the combination of a fuel pump having a fuel inlet and a fuel outlet, fuel supply and delivery passages communicating respectively with said inlet and outlet, a liquid-operated servo-mechanism for controlling the rate of fuel supply from said pump to the fuel delivery passage, a liquid-operated control device for said servomechanism, said control device including a chamber, a liquid-pressure responsive member dividing said chamber into first and second compartments, and means operable by said member for controlling said servo-mechanism, means including a third passage for supplying the first compartment with operating liquid at a pressure which varies with and in proportion to the speed of the pump,

and thereby exposing one side of said member to the pressure of the operating liquid, said third passage having a restriction therein, a fourth passage connecting the second compartment to the fuel supply passage, and thereby exposing the opposite side of said member to the pressure in said fuel supply passage, a fifth passage communicating at opposite ends respectively with said fuel supply passage and said first compartment, and a valve arranged in said fifth passage and operable for establishing and interrupting liquid flow through said fifth passage, and thereby varying the liquid pressure acting on one side of said member, said fifth passage having a restriction therein between said valve and said first compartment.

References Cited in the file of this patent UNITED STATES PATENTS 2,514,674 Schorn July 11, 1950 2,517,313 Hooker et a1 Aug. 1, 1950 2,523,214 Ifield Sept. 19, 1950 2,566,734 Lawrence et al Sept. 4, 1951 2,572,390 Righton Oct. 23, 1951 2,643,514 Jubb June 30, 1953 

